Why use graphs?
A graph turns a boring table of numbers into a picture that tells a story at a glance. You can quickly see:
- Which category has the most or fewest
- How things compare
- Patterns and trends
Bar graphs
A bar graph uses bars to show quantities. Each bar represents a category.
How to read a bar graph:
- Read the title — what is the graph about?
- Check the labels on each axis (x-axis = categories, y-axis = amounts)
- Read where the top of each bar lines up with the scale
Example: Favourite Fruits in Class 4B
From this data we can see:
- Apple is the most popular (8 students)
- Grape is the least popular (3 students)
- Total students surveyed: 8 + 5 + 7 + 3 + 6 = 29
Line plots
A line plot (or dot plot) uses dots or X marks above a number line. Each mark represents one data point.
Great for showing how data is spread out — where are most values? Are there gaps?
Example: Number of books read last month
The data set is: 0, 1, 1, 2, 2, 2, 2, 2, 3, 5
- Mode (most common): 2 books (5 students read exactly 2)
- Range: 5 − 0 = 5
Key vocabulary
| Term | Meaning |
|---|---|
| Mode | The value that appears most often |
| Range | Highest value minus lowest value |
| Scale | The numbering on the axis (by 1s, 2s, 5s, 10s…) |
Read the title
Check the axes
Read the bars
Compare
A graph makes patterns visible at a glance — you can spot the largest, smallest, and differences instantly.
Practice
Use the Favourite Fruits data above (Apple: 8, Banana: 5, Orange: 7, Grape: 3, Mango: 6) for these questions:
How many more students chose Apple than Grape?
Apple: 8, Grape: 3. Difference: 8 − 3 = 5 students.
How many students were surveyed in total?
8 + 5 + 7 + 3 + 6 = 29 students.
Which fruit was chosen by exactly 6 students?
Mango was chosen by 6 students.
A teacher recorded test scores: 75, 80, 80, 85, 85, 85, 90, 90, 95, 100
What is the mode of the test scores?
85 appears 3 times — more than any other score. That makes it the mode.
What is the range of the test scores?
Range = highest − lowest = 100 − 75 = 25.
If a bar graph has a scale going 0, 5, 10, 15, 20 and a bar reaches halfway between 10 and 15, what value does it represent?
Halfway between 10 and 15 is 12.5. Reading between scale marks is an important skill!
Challenge
Quick-Fire Round